Comparing characteristics of malnutrition, starvation, sarcopenia, and cachexia in older adults

Wasting syndromes such as malnutrition, starvation, sarcopenia, and cachexia have been increasingly recognized in health care and are the subject of significant research endeavors internationally. It is the purpose of this chapter to compare the characteristics (definitions and diagnosis, etiology, prevalence and outcomes) of each of these conditions in older adults. Protein-energy malnutrition is a syndrome caused by the inadequate bioavailability of energy and/or protein over time, leading to the catabolism of lean tissues with or without loss of fat mass, occurring most frequently in older adults. Malnutrition prevalence ranges from 10% to 50% depending on the setting. Simple starvation is a physiological state referring to the metabolic alterations, such as hypophosphatemia and the production of ketones as the primary energy source, which are activated in a state of food and nutrient deprivation, but when it causes physiological consequences it is clinically referred to as malnutrition. Starvation-related malnutrition is only diagnosed when proteinenergy malnutrition is caused by food and nutrient deprivation over a long period of time in the absence of disease processes and inflammation. Sarcopenia is the loss of muscle mass, strength, and function that occurs due to age-related changes in physiology and ranges in prevalence from 10% to 50% depending on age group. Cachexia is a complex syndrome which presents with the loss of body weight, predominately skeletal muscle, as a result of metabolic abnormalities related to disease processes. Cachexia may be considered as a type of disease-related malnutrition and ranges in prevalence from 10% to 50% depending on the underlying disease. Malnutrition, starvation, sarcopenia, and cachexia result in the catabolism and subsequent dysfunction of multiple organ systems and skeletal muscle, leading to poor patient outcomes such as physical dysfunction, hospitalizations, poor quality of life, and increased risk of death.